text: /**
   * @author zz85 / http://www.lab4games.net/zz85/blog
   *
   * Two pass Gaussian blur filter (horizontal and vertical blur shaders)
   * - described in http://www.gamerendering.com/2008/10/11/gaussian-blur-filter-shader/
   *   and used in http://www.cake23.de/traveling-wavefronts-lit-up.html
   *
   * - 9 samples per pass
   * - standard deviation 2.7
   * - "h" and "v" parameters should be set to "1 / width" and "1 / height"
   */
  
  v3d.HorizontalBlurShader = {
  
      uniforms: {
  
          "tDiffuse": { value: null },
          "h": { value: 1.0 / 512.0 }
  
      },
  
      vertexShader: [
  
          "varying vec2 vUv;",
  
          "void main() {",
  
          "    vUv = uv;",
          "    gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);",
  
          "}"
  
      ].join("\n"),
  
      fragmentShader: [
  
          "uniform sampler2D tDiffuse;",
          "uniform float h;",
  
          "varying vec2 vUv;",
  
          "void main() {",
  
          "    vec4 sum = vec4(0.0);",
  
          "    sum += texture2D(tDiffuse, vec2(vUv.x - 4.0 * h, vUv.y)) * 0.051;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x - 3.0 * h, vUv.y)) * 0.0918;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x - 2.0 * h, vUv.y)) * 0.12245;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x - 1.0 * h, vUv.y)) * 0.1531;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x, vUv.y)) * 0.1633;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x + 1.0 * h, vUv.y)) * 0.1531;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x + 2.0 * h, vUv.y)) * 0.12245;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x + 3.0 * h, vUv.y)) * 0.0918;",
          "    sum += texture2D(tDiffuse, vec2(vUv.x + 4.0 * h, vUv.y)) * 0.051;",
  
          "    gl_FragColor = sum;",
  
          "}"
  
      ].join("\n")
  
  };
  